For such uses, adhesives called structural adhesives are known, composed of two components, stored separately, one of which is a catalyst intended to carry out the polymerization of the other component which contains monomers.
Structural glues and adhesives comprise three broad families of polymers, which give the bonded joint its structure. These three broad families cross-link in different ways, and are incompatible with each other. They can be classified according to their modulus, characterized by their tensile-shear strength (TS), and their elasticity. These are epoxide-matrix, polyurethane-matrix and methacrylate-matrix adhesives.
Epoxide glues (epoxy/amine polyaddition) have a high modulus and TS ranging up to 40 MPa, but a low elongation of 3-5%.
Polyurethane-based glues (polyol/poly-isocyanate polyaddition) have a low modulus, of the order of 5-10 MPa TS, while having an elongation capable of reaching 100%.
Methacrylate-matrix glues (radical polyaddition) have a high modulus (20 to 30 MPa TS), but a low average elongation, not exceeding 40%.
The methacrylate-based glues have the best compromise between a high modulus, giving the assembly a significant strength with respect to tensile stresses on the substrates, and a good fatigue resistance, contributed by the flexibility of the bonding joint.
Their resistance to ageing and to chemicals is excellent.
Furthermore, the application of the methacrylate-based glues is less demanding that that of the other structural adhesive products.
Document WO 98/23658 describes a curable composition that can be used for coatings or as an adhesive, comprising (a) a polymerizable monomer, (b) a core/shell polymer, and (c) a liquid polymerizable component capable of conferring strength when polymerized, while polymerizable monomers (a) and (c) must be different.
Document FR 07 02485 describes a structural adhesive composition comprising (a) at least one methacrylate ester monomer, (b) at least one elastomer block copolymer, (c) a selected elastomer, and (d) particles formed from a thermoplastic shell and an elastomer core, while component (b) must comprise at least one elastomer block copolymer containing styrene and at least one second monomer.
Document FR 06 11442 describes an adhesive composition that must comprise at least one methacrylate ester monomer; at least one elastomer chosen from polybutadiene, polyisoprene and polychloroprene; as well at least two elastomer block copolymers all comprising styrene among their monomer units.
Document EP 0 357 304 describes an acrylic structural adhesive composition comprising 50-75% of an methacrylate ester monomer; 0-15% of a polymerizable mono- or dicarboxylic acid having ethylenic unsaturations; 10-30% of a core/shell polymer; and 5-20% of an elastomeric polymer. However in practice, such a composition gives rise to problems, both as regards formulation, and also with respect to the application of the composition onto a surface.
Moreover adhesives exist that have a high elongation at rupture (ranging up to approximately 200-250%), but such adhesives have a low tensile/shear strength which prevents their use as structural adhesives.
More generally, the various conventional structural adhesives thus described or proposed have:                elongation at rupture that is too low to allow the assembly of materials that may undergo high expansion;        low elasticity, the corollary of which is polymer creep, an irreversible phenomenon that weakens the bonded joint and reduces its resistance to vibration or repeated stresses;        a cross-linking time that is difficult to accept in industrial installations because it cannot be adapted according to the application, and        joint thickness that is limited in practice to a range of 250 to 300 micrometers.        
Thus there is remains a need to carry out bonding of various materials under cost-effective conditions, without primer or primary adhesive layer, with rapid curing and above all with a durability and resistance to mechanical and/or thermal stresses ensuring that the integrity of the bond and of the bonded pieces is maintained. This requirement is even more important for the decks and/or hulls of vessels, for which the bonding and/or caulking involves wood, particularly teak, and an assembly of metal substrates, polymer substrates and/or a substrate itself made of wood.